Academic literature on the topic 'Sfingosin'

Abstract B cell receptor (BCR) signaling plays an important pathogenic role in chronic lymphocytic leukemia (CLL) enhancing homing and homeostasis of B-CLL cells and favoring the interaction with the pro-survival stromal lymph node microenvironment. Surface expression of CD69 is required to block the cells in lymphoid compartment while Sfingosine-1-phosphate receptor-1 (S1PR1) is necessary for egress of cells to blood. BCR signaling inhibitors such as Ibrutinib and Acalabrutinib, (anti-bruton tyrosine kinase) or Idelalisib (anti-Phosphatidylinositol 3-kinases ) represent a significant therapeutic advance in CLL. At least some of these drugs are distinctive to lead to an initial lymphocitosis due to rapid release of cells from lymphoid organs to blood, where they die. Changes in microRNAs expression characterize clinical progression of CLL with a strong decrease of miR-181b associated with the more aggressive phase of the disease. In this study we demonstrate that miR-181b is part of the BCR pathway in that it influences the anatomical redistribution of CLL cells from lymph nodes into the blood by balancing the expression of CD69 and S1PR1. We co-cultured MEC_01 and pure B-CLL cells in medium supplemented or not with IgM F(ab')2, specific antibodies for BCR. We observed a significant decrease of miR-181b after 24 hrs of BCR stimulation compared with the same cells cultured in medium without IgM F(ab')2. To establish that this effect was due to the stimulation of the BCR, studies were performed on MEC_01 and in pure B-CLL cells treated separately with 1μM Ibrutinib or 1 μM Idelalisib, which are a potent BCR signaling inhibitors. After 1 hours of treatment the relative expression of miR-181b was assessed noting an increase of the transcription of miR, suggesting that the activation of BCR down regulate the expression of miR-181b. To confirm what we observed in vitro, RNA was isolated from B cells of the CLL patients at different time-point before and after treatment with a BTK inhibitor, Acalabrutinib (ACP-196). We observed a marked increase of miR-181b in the patients in therapy with this drugs compared with respective baseline. Since BTK inhibitors lead to the immediate release of CLL cells from lymphoid tissues to circulation, we evaluated whether this miRNA could be involved in this process. To test this hypothesis MEC01 cells were infected with either LV-miR-181b_coGFP or the LV-CTRL_coGFP after which migration was assessed in transwell assays. The Cells (5 × 105 cells/well) were seeded on top of the transwells and allowed to migrate for 4 h. S1P (100 nM) was added to the lower chamber as a chemo attractant. Transwell assay was performed to determine the migratory capacity of MEC-01 GFP+ cells, mimicking spleen (S1P-) vs blood (S1P+) compartments. Our data indicate that enhanced expression of miR-181b accelerate the migration of B-CLL cells. On the same cells we also evaluated the expression of S1PR1 and CD69. We observed that the restoration of miR-181b down regulated CD69 expression and increased the S1PR1. We also demonstrated that both proteins are direct targets and that the regulation on SIPR1 by the miR-181b occurs through a not canonical way. In conclusion, our findings indicate miR-181b is down regulated by BCR stimulation in CLL cells and that its enhanced expression reduced CD69 while increased S1PR1 by direct targeting. This could facilitate the egress from lymphoid tissue to blood and in turn their death. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Author: Denisa Kubátová Supervisor: PharmDr. Andrej Kováčik, Ph.D. Consultant: PharmDr. Lukáš Opálka, Ph.D. Title of diploma thesis: Study of sphingosine, dihydrosphingosine and phytosphingosine in skin barrier models The stratum corneum (SC), the uppermost layer of the skin, localized in the uppermost part of the epidermis, represents the skin barrier of the organism. SC is composed of corneocytes and an intercellular lipid matrix, which is formed by ceramides (Cer), free fatty acids (FFA), and cholesterol (Chol) in an equimolar ratio. Substances from the group of sphingolipids - Cer, are sphingoid bases (for example, sphingosine (S), dihydrosphingosine (dS), phytosphingosine (P)) acylated with a fatty acid (for example, lignoceric acid (LIG)). In the lipid matrix, the metabolic products of Cer (free sphingoid bases) are also present, but their role in SC barrier functions is not clear. Some studies show that Cer with different sphingoid bases, and increased presence of free sphingoid bases, can lead to a change in the permeability of the skin barrier. This work aimed to study the effect of permeability of sphingoid bases on the model membrane permeability. Nine types of membranes were prepared; they...

Charles University in Prague, Faculty of Pharmacy in Hradci Králové Department of anorganic and organic chemistry Candidate: Tomáš Drozen Supervisor: Doc. PharmDr. Kateřina Vávrová, Ph.D. Title of Diploma thesis: Synthesis of ceramide analogues based on 5C sphingosine Ceramides are lipids, in particular sphingolipids. They have many important roles in the organism. Ceramides form the main part of lipid matrix in the stratum corneum, the uppermost skin layer, and take an important part in maintaining skin barrier properties. Membranes of eukaryotic cells also contain ceramides, and both ceramides and their derivatives formed in organism are important signalling molecules. They act as both primary and secondary messengers, participating in regulation of cell growth, apoptosis and inflammatory responses. Although ceramides have been investigated for a long time, there are still many unanswered questions. Fo rthe understanding of the ceramide functions, it is necessary to investigate their movement in the organism and study the effects of their analogs with changed structure. Olefin metathesis is often used for synthesis of analogs with varying chain length or different florescent labels. This thesis describes attempts to synthesise ceramide analogs with very short sphingosine chain, which can be used...

Ceramides are a complex group of lipids, naturally occurring in the uppermost layer of the epidermis, in the stratum corneum (SC). They constitute a major component of extracellular matrix and they are responsible for the skin barrier properties. Diseases such as atopic dermatitis or psoriasis are associated with the decline in content and changes in the composition of ceramides, which lead to the reduction in the protective functions of the skin. Although the importance of ceramides is known, the relationship between their structure and effect on the barrier function is not yet fully elucidated. Earlier studies indicate that the length of ceramide acyl chain affects the skin permeability. It appears that ceramides with short acyl lose the protective properties. First, I have prepared a series of analogues of ceramides with fifteen carbon atoms chain in the sphingosine part and the acyl part of a length of 2, 4 and 6 carbons. Starting substance of the synthesis was N-protected L-serine methyl ester, which was further protected by the formation of a cyclic acetal and subjected to the reduction of the ester to aldehyde. The resulting aldehyde reacted with 1-alcynide in the presence of HMPA. The triple bond was subsequently reduced to a trans-double bond by lithium in ethylamine. After deprotection of...